The present invention generally relates to mechanisms for controlling the dispensing of products from vending machines. More specifically, the present invention relates to a vending machine gearmotor including a mechanism for determining and controlling the position of a gearmotor output shaft. A method for controlling the dispensing of products in a vending machine is also disclosed.
The gearmotor of the present invention may be used to drive a vending machine rotor. Well known in the art, such rotors are axially rotating structures, usually helical or cupped and used to hold and dispense product from a point of storage or display within the machine. In most vending machines, dispensing involves axially rotating the rotor to advance product held between the coils or in the cups of the rotor until the product is released from the rotor and falls to a user accessible area of the machine.
As the amount of rotor advancement needed to release a product varies depending on the size and shape of the product, it is necessary to control the amount of axial rotation of the output shaft of the gearmotor to control the amount of axial rotation of the rotor and, therefore, the advancement of the product. In present gearmotors, this is accomplished through mechanical means, primarily mechanical switches which are tripped by protuberances molded into rotating gear shafts. Such systems require mechanical adjustment of the gearmotor, a timing cam or the use of numerous spacers to adjust for each time a different amount of advancement is needed to compensate for different sized product.
Typically in bottle and can/bottle vending machines, the output shaft of the gearmotor drives the rotor of the vending machine. Typically, the rotor is a half-moon shape in which the product lies on its side. Depending on the size of the product and the internal dimensions of the vending machine, each rotor can accommodate a set number of units of product. Depending on the product, a mechanical cam (typically attached to the output shaft of the gearmotor) will require some adjustment to properly dispense an individual product. For example, if the rotor holds three products and the cam is set to dispense one product, when the cam reaches the first detent position and the mechanical switch is activated stopping the gearmotor, the rotor may rotate to an angular position in which two products are dispensed. To accommodate the difference in package sizes, some machines include removable spacers from which the operator selects to establish the proper configuration to properly dispense the product based on its size. The present invention solves the problems associated with the prior art.
The present invention includes a gearmotor with solid-state controls to sense and control the axial rotational position of the gearmotor""s output shaft and/or motor armature shaft. This control is achieved through the use of pre-programmed control circuitry which calculates the real-time position of the gearmotor output shaft. As such, the present invention is configured to provide different, predetermined amounts of output shaft and machine rotor rotation and, therefore, product advancement, based on software instructions and not mechanical modification. Thus, the present invention permits vending machine stockers to compensate for different sized products without the need of mechanical adjustment.